Gramophone-record.



A. EICHENGRUN.

GRAMOPHONE RECORD. APPLICATION FILED JULY 20,19l2.

1, 175,72. Patented Mar. 14,1916.

5 24/72; EFLQZM ARTHUR EIGHENGRTZTN, 0F BERLIN, GIEIRIWANY.

GRAMOPHONE-REGGRD.

Specification of Letters Patent.

Patented Mar. 14, i lifi.

Application filed July 20, 1912. Serial No. 710,679.

To all whom it may concern Be it known that l, ARTHUR Ercmmom'in, asubject of the German Emperor, residing at 87 Konstanzei'strasse,Berlin, Germany, have invented certain new and useful Improvements inand Relating to Gramophone- Records, of which the following is aspecification- This invention relates to sound records, tablets, disksor other bodies for use in sound recording and sound reproducingmachines.

Sound records used for gramophones and the like apparatus give after avery short use indistinct and impure tone. This is caused bymiscroscopically small injuries to the edges of the sound grooves orphonetic characters. This phenomenon is due to the brittleness of thefoundation material containing shellac, colophonium, asphalt and thelike that is generally used for making such sound records. Numerousattempts have been made to obviate this drawback by replacing the usualfoundation material by elastic substances such as celluloid, xylonite,gallalite, hardened gelatin, ebonite and the like. These materials,however, have not proved altogether satisfactory for this purpose.Celluloid, which was partic-' ularly recommended, is liable gradually tosettle down until its surface become level, the phonetic characters thenbecoming partially or entirely obliterated; moreover celluloid is liableto shrink and its tension then becomes so altered asto warp the record.Apart from this physical change of celluloid the material itself is toohard for the purpose in question and produces a shrill harsh tone, andit is inconvenient to employ.

The present invention aims at obviating these drawbacks and at impartingtothe record body the requisite degree of toughness coupled with asuflicient but not undue degree of hardness, and also at very materiallyimproving the tone and the details of the phonetic record and atsimplifying the process of its manufacture. For this purpose accordingto the present invention the foundation layer or body of the record iscoated with a layer of cellulose ester containing the acetyl group priorto receiving the sound record and said sound record is then impressed inthe layer of the cellulose ester and preferably also in the layer ofother material immediately below said cellulose ester. Record bodiesproduced in this way retain the phonetic characters permanently becausethe layer of cellulose ester containing the acetyl group is not liableto level down like a celluloid layer. Such records are not liable toshrink and in consequence of the plasticity and non-elastic character ofthe layer a fine, soft, mellow tone is obtained.

Owing to the high concentration of the solutions which can be preparedwith cellulose ester containing the acetyl group, they can be applied tothe record disk in one operation without the necessity of successivecoatings or applications. The plasticity of the cellulose estercontaining the acetyl group can be modified or adapted to the materialin conjunction with which it is to be used, that is to say to thematerial forming the underlayer or body. This is of vital importance tothe production of a good tone because it will be obvious that theparticular kind of sound obtained from a record body of one kind ofmaterial (say for example cardboard) will be very different from the oneobtained from a, record body of a widely different material such forinstance a's vulcanite.

A further advantage is that, where the film of the cellulose ester is sothin that the sound record is impressed not only in said film but in theunder-layer the guiding of the needle is efifected by said under-layeras well as by the cellulose ester layer while the cellulose ester willprotect the walls of the sound. record in the under-layer and preventthein fron'i crumbling or being otherwise damaged or defaced.

l have sometimes found it convenient not to make layers of celluloseester containing the acetyl group alone but to employ mixtures of thesame with softening agents such as di-chlorhydrin or with liquid orsolid bodies adapted to impart increased plastic properties to thelayers of cellulose ester such for example as camphor substitutes, andit will be obvious that if desired organic and inorganic fillingmaterials, especially in a finely powdered state may be admixedtherewith. Of inorganic filling materials I have found mineral powderspresenting a certain resistance to the needle especially convenient,such for example as gypsum, kieselguhr, or the like.

The invention is diagrammatically illustrated in the accompanyingdrawings, in which:

Figure 1 represents in section one form of the disk; and Fig. 2 anotherform thereof.

In the said drawings, a represents the foundation plate of resinous orother foundation material, and Z) the covering or layer of celluloseester containing the acetyl. group.

I 0 represents the phonetic characters which it will be observed areimpressed into both the cellulose ester coating and into the foundationplate.

The covering film is produced upon the shellac or other foundation plateeither by coating the latter with a solution of cellulose estercontaining the acetyl group with or without other substances, or bydipping the plates in said liquid or by injecting the liquid thereuponin which case the operation can be effected repeatedly, either byseveral treatments with the same solution or by alternate treatmentswith solutions of different composition or viscosity, and capable ofproducing different degrees of hardness. Suitable solvents for thispurpose are such solvents of cellulose ester containing the acetyl groupas will not, in this mode of employment, exert a dissolving action onthe shellac or other foundation plate such as for example mixtures ofalcohol and benzene (C H Or if desired the layers of cellulose ester canbe made beforehand by allowing the solution to dry in thin sheets orfilms upon any suitable supporting surfaces, or by cutting such thinsheets or films from thicker plates or peeling them from blocks, andthen combining them with the shellac foundation in a suitable mannersuch as by joining them together with a solvent or by warming, in somecases under pressure.

If desired the layer of cellulose ester may be provided with a backing d(Fig. 2) formed of thin paper, silk, tin foil or the like which can beeffected in machines adapted to produce large rolls of such a layer withits backing. Said layer with its backing is then merely laid upon thehot shellac mass, or other foundation and a perfect impression can bemade'since the characters can readily'be impressed 'into' the shellac orother foundation. An easy way of affixing said layer with its backingmay be by means of a suitable adhesive material such as glue.

The disks thus obtained from the shellac or like plate of foundationmaterial with two layers or coatings of cellulose ester; containing theacetyl group can be easily impressed while hot in the known manner andthe surface will take the phonetic writing with ease and at the sametime with greater sharpness than a mere shellac or the like disk withoutthe coating.

It should be remarked that while it is old to make records for soundrecording and sound reproducing instruments from celluloid or to providethem with a coating of celluloid or nitro-cellulose ester or to coatphonographic records with an extremely thin film of cellulose estersubsequent to the impression of the phonetic writing by applying a verythin solution which on evaporation leaves a film that adapts itself tothe contours of the preexisting impression, the novel feature of thepresent invention is that the blank record plate is provided with alayer or film of cellulose ester containing the acetyl group before thephonetic writing is impressed on the plate, which layer is plastic andnon-elastic and quite distinct from the elastic non-plastic layer ofcelluloid; and moreover retains the phonetic characters imparted theretomore permanently than is the case with celluloid or the like.

It will be obvious that if desired in place of shellac or colophonium orthe like resins or other plastic masses as foundation material there maybe employed fibrous or other suitable materials such as cardboard or'the like also that in place of cellulose ester containing theacetylgroup for the coating mixtures of other cellulose esters may beemployed.

What I claim as my invention and desire to secure by Letters Patentis 1. A record blank comprising a backing or foundation and a facinglayer of a composition of cellulose ester containing the acetyl groupand a suitable softening agent.

'2. A'record blank comprising a backing or foundation and a. facinglayer comprising cellulose ester containing the acetyl group, a suitableplasticity ingredlent, and a filling material.

3. A record blank comprising a foundation, a facing layer of acomposition of cellulose ester containing the acetyl group anda suitablesoftening agent, and a spacing or backing layer for said facing layer.

In testimony whereof, I aflix my signature in presence of two witnesses.

ARTHUR EICHENGRUN.

Witnesses HENRY HASPER, VOLDEMAR HAUPT.

